Process of mercerizing a cellulosic material while simultaneously depositing silica thereon



United States Patent PROCESS OF MERCERTZING A QELLULOSIC MA- TERIAL WHILE SIMULTANEUUSLY DEPOSIT- ENG SILKCA THEREON Aubrey A. Hobbs, 710 Airport Road, Marion, N.C. 28752 No Drawing. Filed Nov. 22, B61, Ser. No. 154,357 20 Claims. (Cl. 8115.6)

This application is a continuation-in-part of application Serial No. 78,852 filed December 28, 1960, now abandoned.

This invention relates to textile yarns and threads and a process for producing the same, and more particularly to yarns and threads that have been produced by treating them with colloidal silica and mercerization in order to impart enhanced desirable characteristics to said yarns and threads. 7

The yarns and threads of the invention are characterized by increased tensile strength, added lustre, more smoothness or a gassed effect, and reduced static, which allows the individual ends to be separated more easily in the subsequent quilling operation.

In the prior art, it has been known to treat textile fabrics with silica in order to obtain waterproof results. It has also been a practice to silica treat raw fiber stock prior to spinning as an aid in spinning, and also to improve the tensile strength of the resultant yarn. Nylon sutures have been silica treated in order to increase the coefficient of friction so that more secure surgical knots could be tied.

Heretofore it has been considered impractical to mercerize yarns and threads that have been silica treated by known methods, because the process of immersing yarn and thread in a liquid colloidal silica dispersion, followed by drying the yarns and threads in order to deposit free silica on the fibers by evaporation, reduces the elongation of the yarns and threads to the point that the individual ends break if subjected to the tension of mercerization.

That is, the immersion of the yarn and thread in a silica bath, followed by drying, deposits particles of silica on the individual fibers, which results in an increase of the coefficient of friction of the individual fibers, which in turn results in a reduction of elongation because the frictionally held fibers break under added tension rather than elongating sulficiently to mercerize the yarn and thread.

Single and or unplied yarns have been especially noted for their fragility, and heretofore no one has been able to successfully mercerize a low twist, unplied or single end, spun yarn. By low twist is meant single end spun yarns having a twist multiple of about 3.25 and lower.

Generally speaking, the present invention comprises a continuous process whereby yarn or thread is immersed in a colloidal dispersion of silica and then passed immediately in its wet condition into the caustic of a mercerization bath. The caustic of the mercerization bath precipitates the silica from the colloidal dispersion onto the fibers while they are being shrunk or mercerized by the caustic.

The problem of breakage of the individual yarn or thread ends is thus overcome by the invention because the silica is deposited simultaneously with the application of the tension of mercerization, and the fibers become frictionally engaged simultaneously with the application of the tension. Thus the yarn or thread is not set and made subject to breakage by tension prior to mercerization. Additional advantages of the present process, as will appear more particularly below, are that conventional mercerizing process equipment can be utilized, without the 3 ,297,399 Patented Jan. 10, 1967 purchase of additional equipment, and the silica is deposited by precipitation by the caustic that is used in the mercerizationbath, rather than by evaporation through drying. Further, yarns and threads by the invention can be dyed evenly and uniformly because the uniformity of tension throughout the yarns and threads, along with mercerization, increases their alfinityfor dye. In addition, the process allows single end or unplied yarns to be mercerized because they are strengthened by the silica treatment while being mercerized. The present invention also permits the use of greater tensioning during mercerization with consequent increased strength of the mercerized thread or yarn, as welljas other desirable properties such as Wrinkle resistance for single yarns and crease retention on plied yarns.

Describing the method of the present invention in greater detail,- in one embodiment it comprises the steps of immersing the cotton yarn or thread in a bath of, or otherwse treating it so as to impregnate it thoroughly with, an aqueous dispersion of colloidal silica containing approximately l% by weightof-silica. The bath is maintained at a temperature of about 200% F. and the pH is about 11.0, although under.certainconditions; e.g., where contamination of the caustic baths is no problem, a pH of as low as about 9.8 can be used. 7

The colloidal silica bath also is preferably provided with a small percentage, e.g., 0.5%, of a detergent or'wetting agent in order to enforce the impregnation of the fibers, in which case the temperature of the bath can be maintained at a somewhat lower temperature, e.g,, about F. Generally the wetting agent maybe used of a wide variety of compounds, such asfor example the sodium salts of alkylated benzene sulfonates such as sodium oct-yl benezene sulfonate and sodium-decyl benzene sulfonate; sodium lauryl sulfate, the. sodium salt of methyl stearamide ethionic acid, dio'ctyl sodium-sulfosuccinate and the like. One particular type of wetting agent which has been found especially suitable for the present purposes is any one of a group of higher sodium alkyl sulfates possessing powerful Wetting and emulsifying properties. They are stable in the presence of'ac'ids, alkalies, salts, and hard water and they markedly reducethe surface activity of water solutions eve'n under conditions of high dilution. They are used in kier boiling, mercerizing, carbonizing, felting and scouring and dyeing operations, and in the manufacture of bactericides and anticeptics. 7 One such material is v r C H CH (C H C H CH SO Na) C H CH (C H 2 The wetting agent should be used in amounts by weight of solution from about 0.1 to 5.0%.. In lieu of the Wetting agentthe thread or" yarn canzbe passed through squeeze rolls to enhance the impregnation step or a combination of the two procedures may be employed.

After the above described impregnation the thread or yarn is subjected to the caustic of a mercerization bath while still in the wet condition, which simultaneously mercerizes the thread and deposits silica in the fibers thereof.

Alternatively, the thread or yarn can. be first treated With a bath containing about 1% caustic and one of the above wetting agents in the aforementioned proportions; then rinsed with hot water at about F.'to remove the caustic from the surface of the yarn so none will contaminate the colloidal silica bath, and then passed through the colloidal silica bath at a pH of about 9.8, with subsequent vmercerizing treatment as described previously. This sequence of steps tends to initiate precipitation or cause partial precipitation of the. silica prior to the mercerization step which may be desired under certain conditions.

Another variation is to treat first with water at 190 F. then with the colloidal silica, next with a 1% caustic treat, followed by meroerization. In this way, one can obtain partial or complete precipitation of the silica prior to mercization as desired.

Still another variation is to first treat with a solution of about 1% wetting agent in water at 150 F then treat with the silica bath at about 190 F., followed by mercerization.

One object in subjecting the cellulosic and blended materials to the above process steps prior to mercerization is generally to bring the colloidal suspension on the fibers to a more or less unstable condition so that precipitation of the silica will take place rapidly when the material contacts the caustic of 'the mercerization treatment.

In addition to the above procedures, partial precipitation or instability may be brought about by treatment with one or more of the following types of compounds prior to, during, or after the colloidal silica treatment and before the mercerization step: alkali metal salts of strong organic and inorganic and weak acids, eag. sodium chloride, magnesium sulfate, magnesium phosphate, sodium phosphate, etcj; higher fatty'amine salts, quaternary ammonium, sulfoniurn and phosphonium compounds, alkali salts of ethylenediaminetetracarboxylic acids, and the like.

The following are examplesof the process of the present invention.

' EXAMPLE I Fifty warps of 36s two ply combed cotton yarn, each warp containing 378 ends properly leased, were passed through squeeze rolls and immersed in a vat containing a colloidal dispersion of silica heated to 200 F. The colloidal dispersion of silica was formed by mixing 1 volume of 30% colloidal dispersion of silica in water (by weight) wth 30 volumes of water. The warps were then passed through squeeze rolls-and into another vat containing an identical colloidal dispersion of silica at 200 'F., then through squeeze rolls and into a vat containing water at room temperature, then through squeeze rolls and into a vat containing a 23% aqueous solution of NaOH, all parts by weight, at room temperature. The yarn was next passed through squeeze rolls and into a vat containing water at 135 F., then through squeeze rolls and into a vat containing water at 110 F., then through squeeze rolls and into a vat containing water at room temperature, then through squeeze rolls and into a vat containing a 1 /2% aqueous solution of H 50 by volume, at room temperature. Next the yarn was passed through squeeze rolls and into a vat containing a 1 /2% aqueous solution of H 80 by volume, at room temperature, then through squeeze rolls and into a vatcontaining water at room temperature, then through squeeze rolls and into a vat containing water at room temperature, then through squeeze rolls and into a vat containing enough aqueous solution of ammonia at room temperature to adjust the pH of the yarn to about pH 7, then through squeeze rolls and into a bath containing water at 80 F, then through squeeze rolls and into a vat containing water at 140 F., then through squeeze rolls and into a loop dryer at 175 F. until substantially dry. The resultant yarn had the previously described improved properties.

The above is a continuous process carried out on a conventional warp mercerizing range.

A 37s two cord cotton thread was treated according to the method of Example I, with the exception that the thread was given a water wash at 190 F. prior to the silica treatment, the water wash just prior to the caustic treatment was eliminated, and the caustic was refrigerated to maintain it at 70 F. The thread showed a remarkable improvement in uniformity of elongation, compared with the untreated thread. Five bobbins. selected at random were tested twenty times each for elongation on a Uster single end testing machine. In the following table, each elongation figure represents the average of the twenty figures obtained for each bobbin at break:

Table 1 Bobbin Bobbin Bobbin Bobbin Bobbin 1 2 3 4 5 Untreated, percent 5. 38 4. 80 6. 11 4. 72 5. 67 Coefiicieut of Variation. 12. 99 Treated, percent, 4.17 I 4 45 I 4.18 4. 58 4.34 Coefficient ofVariation. 5. 64

It can be seen from the above results that the coefiicient of variation of the elongation for the treated thread was less than half of that for the untreated thread, indicating that the uniformity of elongation has been greatly enhanced by the process of the present invention. This uniformity, as mentioned above, permits threads and yarns to be dyed more evenly and uniformly because of the uniformity of tension throughout the yarns and threads.

EXAMPLE II Fifty warps of l8s single combed cotton yarn, each warp containing 378 ends properly base, were treated identically as described in Example 1 above, except that the final vat of wash water has a temperature of 100 F., rather than 140 F. Similar enhancement of properties was obtained.

EXAMPLE III Fifty warps of 37s two ply combed cotton thread, each warp containing 378 ends, were treated identically as described in Example I above. Once again the desired properties were achieved.

EXAMPLE IV Fifty warps of 18s single combed spun yarn, made from a blend of 75% cotton and 25% viscose rayon, were treated identically as described in Example II above and similar improvement in properties was noted.

EXAMPLE V Table 2 Oz. Untreated (Average of 200 breaks) 18.43 Treated (Average of 200 breaks) 24.40

The improvement in breaking strength was thus shown to be about 33%.

Although the foregoing examples specify combed yarns and threads, carded cotton yarns and threads, and part waste yarns may be substituted therefor with excellent results. Also, spun cotton yarns and threads that have been blended with various other fibers may be treated by the process Without departing from the scope of the invention.

The foregoing examples have been set forth by way of illustration only, and it is to be understood that changes and additions may be made in the process of the invention by those skilled in the art without departing from the scope and spirit of the invention.

I claim:

1. The method of producing an improved cellulose containing fibrous material having increased tensile strength, added lustre, greater smoothness and improved receptivity -to dyes, comprising the steps of treating said material with an aqueous dispersion of colloidal silica and thereafter subjecting such silica treatedmaten'al while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said material and to deposit silica on the fibers thereof.

2. The method of producing an improved cellulose containing fibrous material comprising the steps of treating said material with an aqueous dispersion of colloidal silica containing about 1% by weight of silica, thereafter subjecting the treated material while in the Wet condition to the caustic of a mercerization bath simultaneously to Inercerized said material and to deposit silica in the fibers thereof.

3. The method of producing an improved cellulosic thread comprising the steps of treating said thread with an aqueous dispersion of colloidal silica containing about 1% by weight of silica at a temperature of about 200 F., thereafter subjecting the treated thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica in the fibers thereof.

4. The method of producing an improved cellulosic thread comprising the steps of treating said thread with an aqueous dispersion of colloidal silica containing about 1% by weight of silica at a temperature of about 200 F. and having a pH of about 11.0, thereafter subjecting the treated thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica in the fibers thereof.

5. The method of producing an improved cellulosic thread comprising the steps of treating said thread with an aqueous dispersion of colloidal silica containing about 1% by weight of silica at a temperature of about 200 F. and having a pH of about 11.0, then removing the excess aqueous dispersion from said thread thereafter subjecting the treated thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica in the fibers thereof.

6. The method of producing an improved cellulosic thread comprising the steps of treating said thread with an aqueous dispersion of colloidal silica containing about 1% by weight of silica at a temperature of about 200 F. and having a pH of about 11.0, then passing said thread through squeeze rolls, thereafter subjecting the treated thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica in the fibers thereof.

7. The method of producing an improved cellulosic thread comprising the steps of immersing said thread in a bath containing an aqueous dispersion of colloidal silica and a wetting agent, thereafter subjecting the thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica on the fibers thereof.

3. The method of producing an improved cellulosic thread comprising the steps of immersing said thread in a bath containing an aqueous dispersion of colloidal silica having about 1% by weight of silica and about 0.1 to 5.0% by weight of a wetting agent, thereafter subjecting the thread While in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica on the fibers thereof.

9. The method of producing an improved cellulosic thread comprising the steps of immersing said thread in a bath containing an aqueous dispersion of colloidal silica having about 1% by Weight of silica and about 0.1 to 5.0% by weight of a wetting agent having the formula C H CH C H C H CH (SO Na C H CH (C 11 2 thereafter subjecting the thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica on the fibers thereof.

10. The method of producing an improved cellulosic thread comprising the steps of immersing said thread in a bath containing an aqueous dispersion of colloidal silica having about 1% by weight of silica and about 0.1 to 5.0% by weight of a wetting agent having the formula C H CH(C H )C H CH(SO N21)C H CH(C H aid 6 bath having a temperature of about F. and a pH of about 11.0, thereafter subjecting the thread while in the Wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica on the fibers thereof.

11. The method of producing a cellulosic thread having improved properties comprising the steps of treating said thread with a solution containing 1% by weight of caustic and about 0.1 to 5.0% by weight of an anionic wetting agent, then rinsing said thread with water to remove the caustic from the surface of the thread, next treating said thread with an aqueous dispersion of colloidal silica, thereafter subjecting the thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica in the fibers thereof.

12. The method of producing a cellulosic thread having improved properties comprising the steps of treating said thread with a solution containing 1% by weight of caustic and about 0.1 to 5.0% by weight of a wetting agent having the formula then rinsing said thread with water at about F. to remove the caustic from the surface of the thread, next treating said thread with an aqueous dispersion of col loidal silica containing about 1% by Weight of silica, thereafter subjecting the thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica in the fibers thereof.

13. The method of producing a cellulosic thread having improved properties comprising the steps of treating said thread with a solution containing 1% by weight of caustic and about 0.1 to 5.0 %by weight of a wetting agent having the formula C H CH(C H )C H CH(SO Na)C H CH(C H then rinsing said thread with water at about 190 F. to remove the caustic from the surface of the thread, next treating said thread with an aqueous dispersion of colloidal silica containing about 1% by weight of silica at a pH of about 9.8, thereafter subjecting the thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and to deposit silica on the fibers thereof.

14. The method of producing a cellulosic thread having improved properties comprising the steps of wetting said thread with water at about 190 F., then treating said thread with an aqueous dispersion of colloidal silica having about 1% by weight of silica and about 0.1 to 5.0% by weight of said wetting agent, next treating said thread with a 1% caustic solution, thereafter subjecting said thread while in the Wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and deposit silica on the fibers thereof.

15. The method of producing a cellulosic thread having improved properties comprising the steps of wetting said thread with Water at about 190 F. containing about 0.1 to 5.0% by weight of a wetting agent, then treating said thread with an aqueous dispersion of colloidal silica having about 1% by Weight of silica and about 0.1 to 5.0% by weight of said wetting agent, next treating said thread with a 1% caustic solution, thereafter subjecting said thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and deposit silica on the fibers thereof.

16. The method of producing a cellulosic thread having improved properties comprising the steps of wetting said thread with water at about 190 F. containing about 0.0 to 5.0% by weight of a wetting agent having the formula C H CH (C 15 C H CH (SO Na C H CH (C H then treating said thread with an aqueous dispersion of colloidal silica having about 1% by Weight of silica and about 0.1 to 5.0% by weight of said wetting agent, next treating said thread with a 1% caustic solution, there- 7 after subjecting said thread while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said thread and deposit silica on the fibers thereof.

17. The treated material produced by the process of claim 1.

18. The thread produced by the process of claim 10.

19. The method of producing a cellulosic material having improved properties comprising the steps of treating said material with a solution containing about 0.1 to about 5.0% by weight of a salt selected from the group consisting of alkali metal salts of strong acids, alkali metal salts of weak acids, higher fatty amine salts, quaternary ammonium, sulfonium and phosphonium compounds, and alkali metal salts of ethylenediaminetetracarboxylic acids, then treating said material with an aqueous dispersion of colloidal silica, then subjecting said material while in the wet condition to the caustic of a mercerization bath simultaneously to mercerize said material and to deposit silica in the fibers thereof.

20. The method of producing a cellulosic material having improved properties comprising the steps of treating said material with an aqueous dispersion of colloidal silica, treating said material with a solution containing about 0.1 to about 5.0% by weight of a salt selected from the group consisting of alkali metal salts of strong acids,

the wet condition to the caustic ofa mercerization bath simultaneously to mercerize said material and to deposit sliica in the fibers thereof.

References Cited by the Examiner UNITED STATES PATENTS 133,101 11/1872 Hitchcock 8-115.6 x 596,464 12/1897 Tubbe 8--l15.6 1,839,168 12/1931 Stampe 117-169 2,104,748 2/1934 Huey et al 8-115.6 X 2,497,519 2/1950 Stevenson 8--125 2,582,590 1/1952 Heeren 117169 3,013,898 12/1961 Dempcy 117169 FOREIGN PATENTS 338,654 11/1930 Great Britain.

NORMAN G. TORCHIN, 'Primary Examiner.

JULIAN S. LEVITT, J. C. CANNON,

Assistant Examiners. 

1. THE METHOD OF PRODUCING AN IMPROVED CELLULOSE CONTAINING FIBROUS MATERIAL HAVING INCREASED TENSILE STRENGTH, ADDED LUSTRE, GREATER SMOOTHNESS AND IMPROVED RECEPTIVITY TO DYES, COMPRISING THE STEPS OF TREATING SAID MATERIAL WITH AN AQUEOUS DISPERSION OF COLLOIDAL SILICA AND THEREAFTER SUBJECTING SUCH SILICA TREATED MATERIAL WHILE IN THE WET CONDITION TO THE CAUSTIC OF A MERCERIZATION BATH SIMULTANEOUSLY TO MERCERIZE SAID MATERIAL AND TO DEPOSIT SILICA ON THE FIBERS THEREOF. 